S-cone signals to temporal OFF-channels: Asymmetrical connections to postreceptoral chromatic mechanisms

Keizo Shinomori, Lothar Spillmann, John S Werner

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Psychophysical tests of S-cone contributions to temporal ON- and OFF- channels were conducted. Detection thresholds for S-cone modulation were measured with two kinds of test stimuli presented on a CRT: a rapid-on sawtooth test and a rapid-off sawtooth test, assumed to be detected differentially by temporal ON- and OFF-channels, respectively. S-cone related ON- and OFF-temporal responses were separated by adapting for 5 min to 1 Hz monochromatic (420, 440, 450, 540, or 650 nm in separate sessions) sawtooth flicker presented in Maxwellian view. Circular test stimuli, with a sawtooth temporal profile and a Gaussian spatial taper, were presented for 1 s in one of four quadrants 1.0°from a central fixation point. A four-alternative forced-choice method combined with a double-staircase procedure was used to determine ON- and OFF-thresholds in the same session following adaptation, the threshold elevation was greater if the polarity of the test stimulus was the same as the polarity of the sawtooth adaptation flicker, consistent with separate ON- and OFF-responses from S-cones. This asymmetrical pattern was obtained, however, only when the adaptation stimuli appeared blue with a little redness. When the adaptation flicker had a clear reddish hue component, the threshold elevation did not depend on the polarity of the sawtooth test stimuli. These results are consistent with a model in which OFF-signals originating from S-cones are maintained by a postreceptoral mechanism signaling redness, but not by a postreceptoral chromatic mechanism signaling blueness.

Original languageEnglish (US)
Pages (from-to)39-49
Number of pages11
JournalVision Research
Volume39
Issue number1
DOIs
StatePublished - Jan 1 1999
Externally publishedYes

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Keywords

  • Color mechanisms
  • OFF-channels
  • Photoreceptors
  • S-cones

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems

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